Interleukin-19 (IL19), IL20, and interleukin-24 (IL24) are members of the interleukin-10 (IL10) cytokine family. All three interleukins bind and signal through the IL20R1/IL20R2 heterodimeric receptor. IL20 and IL24 (but not IL19) are also ligands for the receptor complex composed of IL20R2 and IL22R1 (Parrish-Novak et al., J Biol Chem 2002; 277: 47517-47523; Dumoutier et al., J Immunol 2001; 167:3545-3549). It has been proposed that IL19 and IL20, along with other IL10 family members, form a distinct subfamily of helical cytokines where at least IL19 and IL20 have similar three-dimensional structures (Chang et al., J Biol Chem 2003; 278: 3308-13).
IL20 and its receptors are present in elevated levels in psoriatic lesions (Wei et al., Clin Immunol (2005) 117: 65-72; Rømer et al., J Invest Dermatol 2003; 121, 1306-1311; Wang et al., J Invest Dermatol 2006; 126: 1590-1599; Otkjæmr et al., Br J Dermatol 2005; 153: 911-918) and in synovial fluid of rheumatoid arthritis patients (Hsu et al., Arthritis Rheum 2006; 54: 2722-2733; Kragstrup et al., Cytokine 2008; 41: 16-2). Antagonizing IL20 activity using receptor fragments or monoclonal antibodies has therefore been described as a promising approach for treatment of various inflammatory conditions (e.g., WO9927103, WO0146261, WO2003051384, WO2004085475, and WO2006086396). For example, polyclonal anti-IL20 antibodies were found to be therapeutically effective in a xenograft model of psoriasis (Stenderup et al., Br J Dermatol 2006; 154: 11-35, Abstract P-12; Stenderup et al. Br J Dermatol 2009; 160(2):284-96).
Antigenic epitopes of human IL20 (hIL20), as well as rat or murine monoclonal antibodies binding huIL20, have also been described (e.g., WO2005052000, US20060142550, and WO2007081465). However, no antibodies suitable for patient treatment have so far been provided. The present invention addresses these and other needs in the art.